Fabric softeners are added to the laundry in the last rinse step of machine laundering in order to suppress the “dry stiffness” effect that occurs as the laundry dries. Dry stiffness is caused by the formation of hydrogen bridge bonds between the cellulose fibers. The cationic surfactants of the fabric softener penetrate into the fibers and/or become deposited onto the fiber surface, attach themselves to the negative charges, and thereby attenuate the interactions. The resulting decrease in the stiffness of the laundered item results in reduced effort when ironing, and increased wearing comfort.
Liquid fabric softeners are divided into two types: “normal” fabric softeners having a 1- to 5-wt % concentration of softening compounds, and “concentrated” fabric softeners having a 5- to 80-wt % concentration of softening compounds.
The acceptance of a fabric softener product by users is determined not only by its actual performance but also greatly by the viscosity of the product; medium to high viscosities are preferred by users. For normal fabric softeners, viscosities in the range from 100 to 500 mPas (determined using a Brookfield RV DV II+P viscosimeter, spindle 2, at 20 rpm and 20° C.) are desirable.
With normal fabric softeners in particular, the viscosity after manufacture is often too low, and thickeners are added to the products in order to increase the viscosity. EP 0763592 A1, for example, describes the use of fatty acids, in particular unsaturated fatty acids, as thickeners in fabric softeners.
A demand still exists, however, for maximally effective and inexpensive thickening agents for normal fabric softeners. An object of this invention was therefore to make available a thickened fabric softener, having 1 to 5 wt % fabric-softening compound, that can be manufactured inexpensively.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.